1. Field of the Invention
This invention relates to composite manufacturing. Particularly, this invention relates to techniques for cutting fibers such as glass fibers to be used in composite manufacturing.
2. Description of the Related Art
Some existing methods of cutting fibers, e.g. such as cutting glass fibers as may be used in composite manufacturing, employ two rollers, one having a series of horizontal cutting blades and another having a hard rubber surface. The rollers are rotated together in contact so that when strands of glass fibers pass between them the fibers are broken into short segments by the cutting blades.
U.S. Pat. No. 3,992,967 issued Nov. 23, 1976 to Morris Fram, discloses a fiber cutter for cutting lengths of glass fibers and glass rovings into short lengths includes a cutter roller carrying a plurality of cutting blades and shaped annular means cooperatively associated with a resilient back-up roll means. In operation the force executed between the cutter roller and the back-up roller controls the spacing between the rollers by forcing the shaped annular means into the resilient surface of the back-up roller means. In addition to permitting control of spacing, the coaction of the cutter roller with its shaped annular means and the resilient back-up roll means holds the rollers in alignment, reduces the bounce between the rollers as the blades engage and pass over the back-up roll means and permit force to be used to build the blades in engagement with the back-up roll means without blade breakage.
FIGS. 1A and 1B are schematic diagrams of an example prior art fiber cutting device. FIG. 1A is an isometric view of the typical three rollers of a prior art fiber cutting device 100 and a feed bar 102. FIG. 1B is a side view of the same prior art fiber cutting device 100. The cutting device 100 includes one roller as a cutting head 104 which has blades 114 mounted on its surface. The cutting head 104 rotates clockwise. The adjacent roller is a rubber surfaced anvil roller 106. The anvil roller 106 rotates counter-clockwise. Finally, the upper roller is a feed roller 108, which rotates clockwise against the anvil roller 106 and draws the glass fibers 112 into the space between the cutting head 104 and the anvil roller 106 to be cut. The feed bar 102 is mounted on the upper right-hand side with pins 110 to guide the glass fibers 112 (or strands). In the example, twelve glass strands 112 are shown entering the cutting device 100, spaced substantially evenly across the width of the feed bar 102. Typically, the fibers 112 are long continuous strands, which may be packaged as separate balls (not shown), that each deliver a fiber end drawn from the center. However, sometimes they come in spools (not shown). In some devices, plastic tubes or ceramic eyelets (not shown) are used to feed the strands to the cutting device 100.                The glass fibers 112 are pulled into the nip point between the cutting head and anvil roller 106, and the blades 114 mounted on the cutting head 104 part the fiber 112 through a breaking action and not so much by actually slicing. This is because the glass fiber cannot bend around the sharp radius of the blade as it is squeezed against the rubber surface of the anvil roll and the fiber is brittle enough to fracture. Thus, the blades 114 of the cutting head 104 can be dull by normal standards and still part the glass fiber 112.        
One known problem with fiber cutting devices employing a feed roller 108 like the prior art device 100 described above occurs if any of the fibers 112 should stick to the feed roller 108 surface even momentarily. If this should occur, the fiber 112 will begin to spool around the feed roller 108. The fiber cutting device 100 must then be shut down in order for the fiber 112 to be tediously removed from the feed roller 108 so that the device may be reset for cutting to begin again. Over the years, glass fiber cutting techniques have further evolved.
U.S. Pat. No. 4,287,799 issued Sep. 8, 1981 to Fujita et al., discloses a cutting roller of a glass filament chopping apparatus mounts a plurality of spaced, axially parallel cutting blades 19 held in receiving grooves by retainer strips. The peripheral flange surfaces of the cutting roller on the opposite ends of the roller drum are raised to almost the radius of the cutting blade edges, and serve as driving engagement surfaces when the rotating cutting roller is biased into contact with a feed roller.
U.S. Pat. No. 5,873,291 issued Feb. 23, 1999 to Sand, discloses an apparatus for cutting fibrous reinforcement material in relationship with an ejector nozzle. The apparatus comprises at least two feeding rollers and a rotary cutter which is provided with a substantially cylindrical mantle surface with attachments for a number of knives. These cooperate with a support roller with an elastic surface layer for forming a thread nip. The mantle surface of the cutter is provided with slot-shaped recesses for the fiber thread, which recesses extend peripherally along the mantle surface and between successive knives. The recesses enable the thread to be fed forward by means of the feeding rollers at a feeding rate which deviates from the speed of the cutter, for adaptation of the cutting length of the fiber thread.
U.S. Pat. No. 5,970,837 issued Oct. 26, 1999 and U.S. Pat. No. 6,076,442 issued Jun. 20, 2000 both to Arterburn et al., disclose a type of multi-chopper for cutting strands or ribbon shaped material such as strands of glass fibers, and a method of using this chopper, is disclosed. The chopper has at least two chopper assemblies on a rotating frame. When one chopper assembly needs repair, the frame is rotated which brings a rebuilt or repaired chopper assembly into operating position quickly and also brings the assembly needing repair into a position where it can be worked on while the other chopper is operating resulting in much reduced downtime. The frame of the chopper can rotate around a vertical or horizontal line, or around a line passing through two opposite corners of a frame.
U.S. Pat. No. 6,527,211 issued Mar. 4, 2003 to Bellasalma, discloses a fiber chopper overcoming the disadvantages of the previous cutting rollers for chopping continuous filaments. The apparatus includes a means for feeding continuous fibers to a chopping roller. A spring holds the cutting blades on the chopping roller. The filaments pass between the chopping roller and a feed roller for chopping.
U.S. Pat. No. 6,892,617 issued May 17, 2005 to Knauder, discloses a charging arm for conveying, treating and discharging different starting materials in order to produce glass fiber armored plastic pipes.
Although developments in glass fiber cutting technology has occurred, there is a need in the art for apparatuses and methods for efficiently excluding cut fibers that may be employed in composite manufacturing. Particularly, there is a need for such apparatuses and methods to efficiently start and stop cutting in a well-controlled manner. In addition, there is a need for fiber cutting devices that eliminate the problem of fibers sticking and spooling around the feed roller resulting in lost production time. There is also a need for such apparatuses and methods to provide to deliver cut fibers for molded composite manufacturing. There is further a need for such systems and apparatuses to be cheaper and operate at higher production rates than existing systems and minimizing wasted fiber. These and other needs are met by the present invention as detailed hereafter.